geo hw 8
__________ is when various geologic materials exposed to the same environmental conditions will weather differently depending on their composition.
Differential weathering
Which of the following locations will weather a block of marble the most quickly?
Honolulu, Hawaii
During hydrolysis, ions and clay minerals are produced by the decomposition of which of the following Earth materials?
feldspars
Which of the following rocks would most likely experience sheeting?
granite
How can plants physically weather a rock?
Plant roots exert outward pressures as they grow.
Over time, mass wasting causes __________.
canyons to widen
Why is soil considered an interface within the Earth system?
Changes in the climate in the atmosphere create changes in soil texture and composition. Water from the hydrosphere that is added to soil from various sources allows the soil to be able to sustain plant life, which returns the water to the geosphere when it expires.
Sand dunes are typically dominated by quartz grains and very little other mineral matter. Why does this selection occur?
Quartz is extremely resistant to all forms of chemical weathering.
Both tombstones in Figure 1 are from the same cemetery and were erected within four years of each other. Why is the younger marble tombstone more weathered than the older granite tombstone?
The quartz and feldspars in the granite are more resistant to weathering than the calcite in the marble.
Which of the following climates will have the highest rate of weathering
Warm, wet climates
How can the addition of water make a slope fail, creating a landslide?
Water can easily flow downslope .Water makes the slope material heavier. Water in pore spaces reduces cohesion between particles.
chemical
__________ weathering alters the internal structure of rock materials.
The chemical weathering process known as dissolution is most effective in the breakdown of which of the following minerals?
calcite
salt crystal growth
can contribute to crumbling roadways in areas where salt is spread to melt ice and snow in winter.
Which of the following external processes are clearly active/evident in the image above?
erosion, mass wasting
Considering the following list, which is not an example of chemical weathering?
exfoliation
Which of the following are classifications describing how rock and other material move downslope?
fall, slide, slump, creep, flow
With the addition of water, the minerals in granite rocks chemically weather into other minerals, known as products. Test your knowledge of the by-product of each mineral as a result of chemical weathering by labeling the minerals below with their respective products.
feldspar- clay quartz- no chemical change olivine-limonite
Which of the following is the major contributing factor in all landslides?
gravity
climate
has a crucial influence on the rates of all types of mechanical weathering
sheeting; frost wedging
he fissures formed as a result of __________ in exfoliation domes can be further enlarged by ___________ in areas subjected to seasonal freeze-thaw cycles.
Which of the following scenarios best describes how sheeting will develop in an igneous rock?
A subterranean pluton is exposed at the surface, releasing confining pressure.
How might a wildfire influence mass movement?
Because plants on a slope bind the regolith with their roots and shield the soil surface from raindrops, a wildfire that destroys these plants would render the soil looser and more susceptible to the erosional force of rain.
How are slumps and slides related?
Slumps are a type of slide in the special case where the rupture surface is curved.
hree types of chemical weathering processes are particularly important for transforming minerals within rocks into weathered products. These are hydrolysis, oxidation, and dissolution. Through hydrolysis reactions, minerals are weathered in the presence of water. Hydrolysis takes place when acid rain reacts with rock-forming minerals such as feldspar to produce soluble minerals that are removed in solution. Through oxidation reactions, iron-rich materials transform in the presence of oxygen in the air. Oxidation is responsible for why an apple may turn brown after your cut it open and place it in an open space. And through dissolution, minerals dissolve in water, making their chemical products ions within water. Example: Halite (NaCl) usually forms where ocean water evaporates. On the otherhand, it undergoes dissolution when placed in water. You will sort each example into its category of chemical weathering process.
Salty taste of ocean water - dissolution ( by dissolution of minerals) Feldspar in granite weathering to clay - hydrolysis Red color of rocks in arches national park - oxidation Caves formed in limestone - dissolution Yellow stained rocks that used to contain pyrite before weathering - oxidation
One important relationship between chemical and mechanical weathering is ________.
mechanical weathering can produce smaller pieces of rock that have more surface area for chemical weathering to work on.
How are debris avalanches and flows related?
Debris avalanches are large, rapid flows of rock.
Describe how a soil particle moves downhill during the freeze-thaw process.
During the freeze, a soil particle moves at a right angle away from the surface, and thawing causes the particle to fall back to a slightly lower level.
Which of the following factors does not affect the rate of chemical weathering?
Erosion
How is a fall different from creep?
Falls occur rapidly and in areas with high slope, whereas creep occurs slowly in areas with low slope.
Which type of mass movement event requires the addition of water?
Flow
What force is responsible for mass movement?
Gravity
What is the major distinction between internal and external Earth processes?
Internal processes are driven by the Earth's internal heat energy and external processes are driven by energy from the Sun.
Oxidation
Iron weathers through the process of _______
Which of the following is true of lunar soil when compared with terrestrial soil?
It does not contain air It cannot support life It does not contain organic matter
What rock type is the easiest for a river to cut through?
Shale
The production of tabular slabs of rocks caused by unloading of material overlying igneous bodies is known as _____.
Sheeting
Limestone and marble weather faster than granite because ________.
limestone and marble can be dissolved by weak acids in rain
carbon dioxide
A greenhouse gas called __________ influences the rate of chemical weathering.
Which of the following is a reason the Gros Ventre rockslide took place?
Because the river eroded material at the valley base, there was no support of the material upslope.
Deep soils are characteristic of tropical regions whereas thin rocky soils are characteristic of high latitudes. This is a natural demonstration that ________.
Chemical weathering rates are much higher in the tropics than in high latitudes
Of the five basic controls of soil formation, which factor is the most influential in soil formation?
Climate
In temperate and polar regions, the accumulation of talus slopes at the base of steep, rocky cliffs is most often attributed to which of the following processes?
Frost wedging
Which of the following landslides was caused in part because the underlying sedimentary bedrock was oriented parallel to the slope that failed?
Gros Ventre Landslide (Wyoming)
Of the following processes, which is not an example of mechanical weathering?
Oxidation
carbonic acid
Potassium feldspar weathers in the presence of water containing __________
Three types of chemical weathering processes are particularly important for transforming minerals within rocks into weathered products. These are hydrolysis, oxidation, and dissolution. Through hydrolysis reactions, minerals are weathered in the presence of water. Hydrolysis takes place when acid rain reacts with rock-forming minerals such as feldspar to produce soluble minerals that are removed in solution. Through oxidation reactions, iron-rich materials transform in the presence of oxygen in the air. Oxidation is responsible for why an apple may turn brown after your cut it open and place it in an open space. And through dissolution, minerals dissolve in water, making their chemical products ions within water. Example: Halite (NaCl) usually forms where ocean water evaporates. On the otherhand, it undergoes dissolution when placed in water. You will sort each example into its category of chemical weathering process.
Salty taste of ocean water - dissolution ( by dissolution of minerals) Feldspar in granite weathering to clay - hydrolysis Red color of rocks in arches national park - oxidation Caves formed in limestone - dissolution Yellow stained rocks that used to contain pyrite before weathering - oxidation
Which of the following correctly states the role of rivers and mass wasting in the formation of the Grand Canyon?
The Colorado River erodes downward, then mass-wasting processes move material from high to low areas, then the Colorado River transports material downstream.
Pre-existing rocks are broken down into smaller particles by which of the following processes?
Thermal expansion Frost wedging Unloading
How can the creation of ice result in physical weathering?
Water expands in volume when freezing, exerting pressure on a container.
How did weathering destroy New Hampshire's Old Man in the Mountain?
Water migrated along fractures in the rock, where it froze and wedged the rock apart.
The Gros Ventre slide is evident today by __________.
a scar, runout area, and landslide debris filling the valley
A __________ acted as a sliding surface across which material moved downhill during the Gros Ventre Slide.
clay layer
Quartz is quite resistant to weathering and is an important component of ________.
clays in swamps
Which of the following climates would have the greatest degree of ice wedging?
cold in the winter, warm in the summer, and with moderate precipitation
The weather conditions that least favor chemical weathering are ________ and ________,
cool; dry
Which of the following triggers generated the 1958 landslide and tsunami at Lituya Bay, Alaska?
earthquake
Look at the descriptions below of scenarios and determine whether the scenario inhibits weathering or enhances weathering.
limits weathering: Rows of trees are planted on the border of a field to slow the wind and deflect it upward. Promotes weathering: Humans remove trees and other vegetation in order to develop an area of land. LIchens, which secrete acids, are present on the surface of a rock. Animals burrow into the ground loosening the soil. Consistent grazing by a herd of cattle.
Creep is __________.
mass wasting by the gradual downhill movement of sediment, influenced by freeze-thaw or wet-dry cycles
In this activity, you will explore and test your knowledge about triggers of four mass movement types. Slump: occurs on curved surfaces and involves the movement of unconsolidated materials. Slopes are considerably high in areas where a slump occurs. Flow: occurs when material moves downslope as a viscous fluid. Fall: this involves the freefall of rock pieces or masses. Fall occurs on slopes that are too steep for loose material to remain on the surface. Many falls occur when freeze and thaw cycles or plants roots weaken rocks to the point where gravity takes over. Creep: this involves the gradual downhill movement of soil or rock pieces. The major factor that facilitates this process is alternate expansion and contraction by freeze and thaw.
Slump-triggered by curved oversteepened slopes. Flow-triggered by large amount of water and steep slope. Creep-triggered by repeated freezing and thawing of the the soil along a gentle slope Fall-triggered by wedging or plant activites on a steep slope.
biological activity
The break down of rock by moving fresh materials to the surface by burrowing animals is an example of mechanical weathering due to
Define mass wasting.
The downslope movement of sediment and rock under the direct influence of gravity.
Which of the following statements is true regarding the aftermath of the Gros Ventre rockslide?
The rockslide debris dammed up the river and formed a lake.
What are the two sources of energy for the Earth system?
The sun, which drives external processes, and heat inside the Earth, which drives internal processes
What would likely happen to a fence on a hill over time if the fence were built perpendicular to the hill's slope?
The top of the fence would likely bend uphill as creeping rocks moved under the fence and pushed the fence bottom downslope.
Why would trees be J-shaped?
The trunks become tilted in the downhill direction due to creep, but continue to grow toward the sun.
Look at the image carefully. You will see several processes and features. Some of these are agents of mass wasting while others have resulted from the processes of mass wasting itself.Which of the following features is the result of mass wasting?
boulders
A __________ is a common result of creep
broken retaining wall
Which landscape is most prone to generating landslides?
mountains
What is mass movement?
movement of material under the influence of gravity alone
The map below is the spatial representation of the soil distribution across the globe. You will determine the most dominant soil type in each subregion of the world. Northern part of South America the american southwest the american midwest the sahara desert, northern africa other regions
oxisols aridisols molisols entisol gelisols
When sheeting develops in an igneous pluton, fractures will develop in an orientation __________ to the direction of expansion.
perpendicular
The chemical weathering process known as oxidation would be most effective in the breakdown of which of the following Earth materials?
pyroxenes
Heavy rainfall caused the clay to lubricate and the sandstone to become __________.
saturated and heavy
A __________ is formed when vertical incision by a stream is the primary process, with relatively minimal mass wasting.
slot canyon
Which of the following is associated with creep?
slow and subtle movement of material
When a rock is mechanically weathered, __________________.
the surface area of the rock is increased, which allows a greater amount of chemical weathering to occur.
What changes are occurring in the igneous pluton that would result in sheeting?
volume increase
